VISIBLE LIGHT ENCRYPTION METHOD, DECRYPTION METHOD, COMMUNICATION DEVICE AND COMMUNICATION SYSTEM

• US 20150146871A1
• Filed: 01/29/2015
• Published: 05/28/2015
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: Kuang-Chi Intelligent Photonic Technology Ltd. (Kuang-Chi Technologies Co., Ltd.), Epitopix, LLC (Vaxxinova GmbH)
• Original Assignee: Kuang-Chi Innovative Technology Ltd. (Shenzhen Dapeng Kuang-Chi Lianzhong Technology Ltd. LP)
• Inventors: LIU, Ruopeng, LUAN, Lin, XIAO, Guangjin
• Granted Patent: US 10,250,384 B2
• Time in Patent Office: Days
• US Class Current: 380/256
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 9/0852 Quantum cryptography transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

The present invention discloses a visible light encryption method, a decryption method, a communication device and a communication system. The method includes: receiving a visible light signal from a transmit end, where the visible light signal is encrypted at the transmit end by using a key; and obtaining the key, and decrypting the visible light signal according to the key, where the obtaining the key includes: obtaining a key corresponding to a state of a state machine of a receive end; or, obtaining indication information according to the visible light signal and obtaining the key according to the indication information, where the indication information is used to obtain the key. The present invention solves a problem of decryption failure in visible light encryption and decryption, and improves accuracy of decryption.

Claims

1. A visible light signal decryption method, comprising:

receiving a visible light signal from a transmit end, wherein the visible light signal is encrypted at the transmit end by using a key;

obtaining the key, and decrypting the visible light signal according to the key, wherein the obtaining the key comprises;

obtaining a key corresponding to a state of a state machine of a receive end;

or, obtaining indication information according to the visible light signal and obtaining the key according to the indication information, wherein the indication information is used to obtain the key;

wherein the obtaining indication information according to the visible light signal and obtaining the key according to the indication information, wherein the indication information is used to obtain the key comprises;

converting the received visible light signal into a digital signal;

decomposing the digital signal into a signal that comprises a pseudocode sequence indicator and a pseudocode signal;

querying a pseudocode sequence corresponding to the pseudocode sequence indicator, wherein the pseudocode sequence is the key;

decrypting the pseudocode signal according to the pseudocode sequence;

wherein the decomposing the digital signal into a signal that comprises a pseudocode sequence indicator and a pseudocode signal, and querying a pseudocode sequence corresponding to the pseudocode sequence indicator, comprise;

decomposing the digital signal into a device addressing code and a first integrated signal;

decomposing the first integrated signal into the pseudocode sequence indicator and the pseudocode signal; and

determining legality of the pseudocode sequence indicator according to a device addressing code, and if the pseudocode sequence indicator is legal, querying the pseudocode sequence corresponding to the pseudocode sequence indicator.

2. The method according to claim 1, wherein the querying the pseudocode sequence corresponding to the pseudocode sequence indicator comprises:

determining, according to a received pseudocode sequence indicator, whether the pseudocode sequence indicator is legal;

querying, when the pseudocode sequence indicator is a large number that is not cyclic in ascending order, the received pseudocode sequence indicator according to the device addressing code;

if the pseudocode sequence indicator is less than or equal to the received pseudocode sequence indicator, determining that the pseudocode sequence indicator is invalid;

otherwise, determining that the pseudocode sequence indicator is legal;

or

querying, when the pseudocode sequence indicator is a large number that is not cyclic in descending order, the received pseudocode sequence indicator according to the device addressing code;

if the pseudocode sequence indicator is greater than or equal to the received pseudocode sequence indicator, determining that the pseudocode sequence indicator is invalid;

otherwise, determining that the pseudocode sequence indicator is legal;

if the pseudocode sequence indicator is legal, querying the pseudocode sequence corresponding to the pseudocode sequence indicator; and

if the pseudocode sequence indicator is illegal, giving a prompt of an incorrect password.

3. The method according to claim 2, wherein the method further comprises:

querying ID information corresponding to the device according to the device addressing code, and comparing the ID information with ID information obtained by decoding; and

if the same, determining that the ID is legal, and outputting legal ID information.

4. The method according to claim 3, wherein the method further comprises:

controlling a corresponding device according to the legal ID information.

5. The method according to claim 2, wherein after the converting the received visible light signal into a digital signal, the method further comprises:

demodulating the digital signal.

6. The method according to claim 1, wherein the obtaining indication information according to the visible light signal, wherein the indication information is used to obtain the key comprises:

determining a clock change parameter of the transmit end and a clock change parameter of the receive end according to the visible light signal;

determining a clock quickness or slowness factor of the transmit end according to the clock change parameter of the transmit end and the clock change parameter of the receive end; and

updating clock information of the transmit end at intervals of a preset time according to the clock quickness or slowness factor of the transmit end, wherein the clock information of the transmit end is stored locally at the receive end and is used to obtain indication information of the key.

7. The method according to claim 6, wherein the clock change parameter of the transmit end refers to an actually elapsed standard time corresponding to a unit time of system time of the transmit end, and the clock change parameter of the receive end refers to an actually elapsed standard time corresponding to the unit time of system time of the receive end, wherein the actually elapsed standard time is measured by using a system period of a crystal oscillator of the receive end as a unit;

and

wherein the clock quickness or slowness factor of the transmit end is a ratio of the actually elapsed standard time corresponding to the unit time of the system time of the receive end to the actually elapsed standard time corresponding to the unit time of the system time of the transmit end.

8. The method according to claim 7, wherein the preset time is a preset time of the system time of the receive end;

upon elapse of every preset time, an error of the clock information that is of the transmit end and locally stored at the receive end is a result of subtracting a product of the clock quickness or slowness factor of the transmit end and the preset time from the preset time; and

the updating clock information that is of the transmit end and locally stored at the receive end comprises;

subtracting the error from the clock information of the transmit end that is stored locally.

9. The method according to claim 8, wherein the actually elapsed standard time corresponding to the unit time of the system time of the transmit end is obtained by measuring the duration of a light pulse of the visible light signal at the receive end, wherein the visible light signal is received from the transmit end, and the standard time is denoted by M·

T_{2 system} by using the system period of the crystal oscillator of the receive end as a unit; and

the actually elapsed standard time corresponding to the unit time of the system time of the receive end is calculated as (T_{0 nominal}·

f_{2 nominal})·

T_{2 system}, wherein T_{0 nominal} is nominal duration of a light pulse of the visible light signal, f_{2 nominal} is a nominal frequency of the crystal oscillator of the receive end, and T_{2 system} is the system period of the crystal oscillator of the receive end.

10. The method according to claim 9, wherein the measuring the duration of a light pulse of the visible light signal at the receive end, wherein the visible light signal is received from the transmit end comprises:

converting the visible light signal received from the transmit end into a digital signal; and

counting how many (T_{2 system})s have elapsed from a start of a high level or a low level of a pulse of the digital signal until an end of the high level or the low level, wherein the counted number is M.

11. The method according to claim 6, further comprising:

whenever the visible light signal is received from the transmit end subsequently, repeating the steps from the step of determining a clock change parameter of the transmit end and a clock change parameter of the receive end to the step of updating the stored clock information of the transmit end.

12. The method according to claim 1, wherein the obtaining a key corresponding to a state of a state machine of a receive end and decrypting the visible light signal according to the key comprises:

obtaining keys corresponding to a current state of the state machine of the receive end and at least one state before and/or after the current state, and using the keys to decrypt the visible light signal, wherein the visible light signal is encrypted by using a key that varies with the state of the state machine of the transmit end;

wherein the using the keys corresponding to a current state of the state machine of the receive end and at least one state before and/or after the current state to decrypt the visible light signal comprises;

decrypting the visible light signal by using the keys corresponding to the current state and each state of the at least one state before and/or after the current state in preset order until the visible light signal is decrypted successfully or until the keys corresponding to the current state and all states of the at least one state before and/or after the current state have been used for decrypting the visible light signal;

or

using the key corresponding to the current state of the state machine of the receive end to decrypt the visible light signal; and

continuing to decrypting the visible light signal by using a key corresponding to each state of the at least one state before and/or after the current state in preset order until the visible light signal is decrypted successfully or until the keys corresponding to all states of the at least one state before and/or after the current state have been used for decrypting the visible light signal, if the decryption performed for the visible light signal by using the key corresponding to the current state of the state machine of the receive end fails.

13. The method according to claim 12, further comprising:

obtaining the identifier of the transmit end from the visible light signal, the communication data is encrypted by using the key that varies with the state of state machine of the transmit end, the identifier of the transmit end is not encrypted, and communication data correlated with the identifier of the transmit end is stored locally at the receive end;

wherein if the communication data obtained as a result of decrypting the visible light signal by using the keys corresponding to the current state of the state machine of the receive end and one state among at least one state before and/or after the current state is the same as the communication data correlated with the identifier of the transmit end and stored locally at the receive end, the decryption performed for the visible light signal by using the key corresponding to the one state succeeds;

otherwise, the decryption fails.

14. A communication device, comprising:

a receiver, configured to receive a visible light signal from a transmit end and output a digital signal, wherein the visible light signal is encrypted at the transmit end by using a key;

or a visible light signal is at least partially encrypted on the transmitting device by using a key that varies with a state of a state machine of the transmitting device;

the decoder is configured to use keys corresponding to a current state of the state machine of the communication device and at least one state before and/or after the current state to decrypt the visible light signal;

a decoder, configured to obtain the key, and decrypt the visible light signal according to the key, wherein the obtaining the key comprises;

obtaining the key corresponding to a state of a state machine of a receive end;

or, obtaining indication information according to the visible light signal and obtaining the key according to the indication information, wherein the indication information is used to obtain the key;

the decoder specifically comprises;

a pseudocode sequence indicator decomposing unit, configured to decompose the digital signal into a signal that comprises a pseudocode sequence indicator and a pseudocode signal;

a pseudocode sequence querying unit, configured to query a pseudocode sequence corresponding to the pseudocode sequence indicator, wherein the pseudocode sequence is the key; and

a convolutional decoder, configured to perform a logical operation on the pseudocode sequence and the pseudocode signal and output a logical operation result;

wherein

the decoder further comprises a device addressing code decomposing unit, configured to decompose the digital signal into a device addressing code and a first integrated signal;

the pseudocode sequence indicator decomposing unit is configured to decompose the first integrated signal into the pseudocode sequence indicator and the pseudocode signal; and

the pseudocode sequence querying unit is configured to determine legality of the pseudocode sequence indicator according to the device addressing code, and if the pseudocode sequence indicator is legal, query the pseudocode sequence corresponding to the pseudocode sequence indicator.

15. The device according to claim 14, wherein

the receiver receives a visible light signal from a transmitting device, wherein the visible light signal is at least partially encrypted on the transmitting device by using a key that varies with a state of a state machine of the transmitting device;

the decoder is configured to use a key corresponding to the current state of the state machine of the communication device to decrypt the visible light signal; and

if the decryption of the visible light signal by using the key corresponding to the current state of the state machine of the communication device fails, continue to

decrypts the visible light signal by using a key corresponding to each state of the at least one state before and/or after the current state in preset order until the visible light signal is decrypted successfully or until the keys corresponding to all states of the at least one state before and/or after the current state have been used for decrypting the visible light signal;

or

the decoder decrypts the visible light signal by using keys corresponding to the current state and each state of the at least one state before and/or after the current state in preset order until the visible light signal is decrypted successfully or until the keys corresponding to the current state and all states of the at least one state before and/or after the current state have been used for decrypting the visible light signal.

16. The device according to claim 14, wherein

the receiver is configured to receive the visible light signal from the transmit end;

and

the decoder comprises;

a clock change parameter determining module, which determines a clock change parameter of the transmit end and a clock change parameter of the communication device according to the visible light signal received from the transmit end;

a clock quickness or slowness factor determining module, which determines a clock quickness or slowness factor of the transmit end according to the clock change parameter of the transmit end and the clock change parameter of the communication device; and

a clock information adjusting module, configured to update clock information of the transmit end at intervals of a preset time according to the clock quickness or slowness factor of the transmit end, wherein the clock information of the transmit end is stored locally in the communication device.

17. The device according to claim 16, wherein the clock change parameter of the transmit end refers to an actually elapsed standard time corresponding to a unit time of system time of the transmit end, and the clock change parameter of the communication device refers to an actually elapsed standard time corresponding to the unit time of system time of the communication device, wherein the actually elapsed standard time is measured by using a system period of a crystal oscillator of the communication device as a unit.

20. A communication system, comprising a communication device according to claim and a communication device according to claim 14.

18. A visible light signal encryption method, comprising:

encrypting data by using a key; and

transmitting the encrypted data as a visible light signal, wherein the key varies with a state of a state machine of a transmit end, or the visible light signal carries indication information used to obtain the key;

wherein in a case that the visible light signal carries the indication information, the encrypting data by using a key and transmitting the encrypted data as a visible light signal comprises;

encoding a generated pseudocode sequence and the data to obtain a pseudocode signal, wherein the pseudocode sequence is the key;

integrating a pseudocode sequence indicator corresponding to the pseudocode sequence into a header of the pseudocode signal to obtain an integrated signal that comprises the pseudocode sequence indicator and the pseudocode signal, specifically comprises;

integrating the pseudocode sequence indicator corresponding to the pseudocode sequence into the header of the pseudocode signal to obtain a first integrated signal;

integrating a device addressing code into a header of the first integrated signal to obtain a second integrated signal; and

sending the integrated signal in a form of visible light.

19. A communication device, comprising:

an encryption device, configured to encrypt data by using a key; and

a transmitting unit, configured to transmit the encrypted data as a visible light signal, wherein the key varies with a state of a state machine of a transmit end, or the visible light signal carries indication information used to obtain the key;

wherein

the encryption device comprises;

a pseudocode generator, configured to output a pseudocode sequence and a corresponding pseudocode sequence indicator;

a convolutional encoder, configured to perform a logical operation on the pseudocode sequence and the data, and output a pseudocode signal; and

a pseudocode sequence indicator integrating unit, configured to integrate the pseudocode sequence indicator into a header of the pseudocode signal, and output an integrated signal that comprises the pseudocode sequence indicator and the pseudocode signal, wherein the pseudocode sequence is the key, and the pseudocode sequence indicator is the indication information; and

the transmitting unit is configured to send the integrated signal in a form of a visible light signal;

wherein

the pseudocode sequence indicator integrating unit is further configured to integrate the pseudocode sequence indicator into the header of the pseudocode signal, and output a first integrated signal;

the encryption device further comprises a device addressing code integrating unit, configured to integrate a device addressing code into a header of the first integrated signal and output a second integrated signal; and

the transmitting unit is configured to send the second integrated signal in a form of a visible light signal.